WO2008012466A2

WO2008012466A2 - Improved cutting wheel

Info

Publication number: WO2008012466A2
Application number: PCT/FR2007/051708
Authority: WO
Inventors: Dominique Font; Michel Oudart
Original assignee: Ocv Intellectual Capital, Llc
Priority date: 2006-07-26
Filing date: 2007-07-23
Publication date: 2008-01-31
Also published as: ATE523617T1; EP2066832B1; RU2431005C2; EP2066832A2; WO2008012466A3; MX2009000967A; US20100089213A1; CN101495684A; RU2009102291A; TW200829525A; JP2009544557A; BRPI0714686A2; FR2904331B1; KR20090033453A; FR2904331A1; MY143883A; ES2377700T3; CN101495684B; JP5097205B2

Abstract

Cutting wheel (19) for cutting continuous filaments into predetermined lengths, comprising a supporting member consisting of a rotary drum fitted with blades (22) set at right angles on its periphery and, between the blades (22), members whose function is, under centrifugal force, to compress the filaments (11) against the surface of a supporting drum, cut the filaments into lengths (14), and eject the cut lengths, the filament compressing members being fins mounted on a deformable ring (26, 27a, 27b) located under the base of the blades (22) with its axis coinciding with the axis of rotation of said cutting wheel (19), which wheel is characterized in that the deformable ring (26, 27a, 27b) comprises on each side a straight parallel wall extending from the base of the deformable ring (26, 27a, 27b) to the base of the fins.

Description

Advanced cutting wheel

The present invention relates to the field of manufacturing cut son high performance material, or son thermoplastic material, including glass son, and more specifically relates to improvements made to a cutting wheel.

Many devices are known capable of producing such fabrications. These systems generally comprise at least one die from which glass threads are stretched and fed into a cutting device most often constituted by a "cutting wheel" equipped with a multitude of blades whose relative spacing contributes cutting the fiber to the desired length and a cutting wheel referred to as "anvil wheel" usually consisting of an elastomeric tire overmoulded or attached to a removable rim fixed on the cutting machine. The continuous cutting of the fiber is obtained by the high speed rotation of this wheel assembly and the pressurization of the cutting wheel on the anvil wheel by means of a suitable clamping means.

Glass cutting processes for several decades have become continuous processes in which the glass son are directly cut at die exit after drawing. These so-called "direct" or "direct die" processes are high speed processes in which the cutting speed is compatible with the drawing speed of the yarns.

During the cutting process, the cutting wheel and anvil wheel must ensure that:

- the cut remains constant for the longest periods possible,

- the components of the wheels must maintain their integrity and not adversely affect the safety of the personnel.

- the cost of consumables must be as low as possible.

More particularly, it can be seen that the fiber cutting quality, in particular its density and its dynamic integrity, is directly related to the suitability of the materials involved (constituting the blades and the wheel against) to retain their characteristics (conservation of the geometric parameters of the blades, resistance to abrasion wear and notches of reelastomer anvil wheel).

The first major difficulty to solve in section under die is the ability of the wheel to cut the fiberglass while stretching at high speed without slippage.

The stretching operation without sliding is difficult. Indeed, after a cutting operation, the next blade (sometimes distant from the previous one by only 3 mm), presses the fiberglass at the risk of cutting and losing it because the latter is pulled back by fiberizing tension.

Failure to respect this constraint would lead to the production of cut son of random length less than the desired length.

Moreover, at the time of cutting, the wet fibers are bonded to one another by the capillary forces alone and at the moment of the shock exerted by the blade this fragile edifice could explode and lead to the production of a set of fibrils (commonly called fine ").

In addition, after cutting, the cut element has a tendency to jam between the two consecutive blades by bracing effect, to avoid that each turn of cutting wheel elements are packed between the blades and lead to a generalized jamming of the system, it is necessary that a particular device exerts an extraction force which ejects the cut strand off the blades and this just after the cutting zone.

Cutting wheels are known comprising, on the one hand, a support member consisting of a rotating elastomer drum and, on the other hand, blades arranged perpendicularly to its periphery and, between the blades, members to be secured under the belt. The effect of the centrifugal force is the succession of following steps: the compression of the wire against the surface of a support drum for its drawing, the cutting of the wire and the ejection of the cut sections.

The members which provide the compression of the wire are constituted by fins secured to a deformable ring, generally based on elastomer, for example polyethylene, disposed under the base of the blades and whose axis coincides with the axis of rotation of the cutting wheel. These wheels cutting are satisfactory and meet the requirements mentioned above.

Nevertheless, the inventors have found, by using wheels of this type for production volumes of large cut sections and high speeds, that it was very difficult or impossible to obtain satisfactory results.

The inventors have sought the origin of the phenomenon which causes a limitation of the cutting speeds achieved.

After analysis, it turned out that an uncontrolled deformation of the blades, and more particularly a deflection of the blades (all the more important that the cutting wheel is motorized and the number of dies is important) between their point d support during the cycle stretching, cutting, ejection cut son was the source of the problem.

More specifically, under the effect of this deflection of the blades, the blades tend to shorten and generate a heating and softening at their support zone with clamping rings positioned on both sides of the deformable ring, these rings exerting their clamping force on inclined surfaces of the blades. Under the effect of the softening of the clamping rings, a lateral clearance is created at the clamping zone with the blades, which generally leads to their breaking.

The present invention proposes to provide a solution to all of these constraints by proposing an improved cutting wheel technology which allows high cutting speeds and a greater number of dies.

For this purpose, the cutting wheel, intended to cut continuous son in sections of a predetermined length, comprising a support member consisting of a rotary drum equipped with blades arranged perpendicularly to its periphery and, between the blades, organs to ensure under the effect of the centrifugal force the compression of the son against the surface of a bearing drum, and then cutting the son in sections, and the ejection of the cut sections, the members ensuring the compression of the son being constituted by fins secured to a deformable ring disposed under the base of the blades and whose axis coincides with the axis of rotation of said cutting wheel is characterized in that the deformable ring comprises on each side a parallel right flank extending from the base of the ring deformable to the base of the fins.

Thanks to the use of a deformable ring with straight flanks extending over the entire diameter, it is possible, during the immobilization of the blades by clamping rings, to induce strictly normal clamping stresses at the side walls of the the deformable ring and which do not thus cause, during the high speed rotation of the cutting wheel, a deformation of the clamping rings in their area of contact with the blades. The deformable ring eliminates the deflection of the blades and therefore their degradation. The right flanks of the deformable ring prevents its fusion by the fact that all efforts are distributed over a larger support surface.

In preferred embodiments of the invention, one or more of the following may also be used:

- The deformable member is at least in two parts, a spacer separating the two parts and is mounted concentrically with respect to the axis of rotation of the drum and the toe serving as a fulcrum to said blades between their two ends ,

the blades are, on the one hand, immobilized at their ends and on the other hand rest at the level of at least one point situated between its ends,

- The ends of the blades fit into slots in two rings mounted face to face, concentrically to the axis of rotation of the drum.

the ends of the blades are held at the bottom of the slots made in the rings using a pair of elastomer rings and a pair of flanges, said flanges being adapted to induce clamping stresses at the level of the elastomer rings.

the flanges and the elastomer rings are mounted face to face, concentrically to the axis of rotation of the drum, all or some of the parts selected from the flanges, the elastomer rings, the rings, are symmetrical parts,

the deformable member comprises a ring provided at its periphery with a plurality of fins, the fins and the ring forming a monolithic assembly,

the fins and the ring are made of different materials,

a space is provided between two contiguous fins and is delimited by the connecting surface between the base of the fins and the base of a blade,

during operation, the upper face of the fins describes a cylindrical surface of revolution whose radius is different from that of the circle passing through the top of the cutting edge of the blades;

the distance between the two rays is a few tenths of a millimeter.

According to another aspect of the invention, it also relates to a cutting machine intended for the manufacture of cut yarns for technical use, in particular yarns made of thermoplastic material and especially glass yarns, said machine comprising a three-dimensional chassis having three sides or more, at least one cutter assembly secured to one side of said frame, said cutter assembly using a cutting wheel as previously described and an anvil wheel.

Other features and advantages of the invention will become apparent from the following description of several of its embodiments, given by way of non-limiting example.

FIG 1 is a schematic view of the general implementation of the device and associated equipment for stretching continuous filaments of glass from a plurality of sources,

FIG 2 is a schematic perspective view of the various parts constituting the cutting wheel according to a first embodiment,

FIG 3 is a schematic perspective view of the different parts constituting the cutting wheel according to a second embodiment, FIGS. 4 and 5 are schematic partial sectional views of a cutting wheel and an anvil wheel in various cut length configurations.

Figures 6 and 7 are schematic views of the embodiments illustrated in Figures 2 and 3.

The production line, shown schematically in Figure 1, comprises upstream at least one die 10 fed from molten glass or glass beads by a not shown feed device. The die (s) 10, generally made of rhodium-plated platinum and heated by the Joule effect, are provided at their lower part with a plurality of orifices from which a plurality of filaments 11 are stretched mechanically. These filaments forming at least one sheet, are coated with a lubricant sizing product, commonly called sizing, by passing on a coating device 12, before being joined in the form of son by assembly rollers 13. The son 14 thus formed are fed by means of return pulleys 15 to a guiding device 16, for example a comb, before being introduced into the cutting machine 17 composed of a support drum 18 (commonly called a wheel anvil) and a blade drum, commonly referred to as a cutting wheel 19.

According to FIG. 1, the stretching is obtained solely by the action of the cutting device whose operation will be described later; it could also be performed by an auxiliary drawing device, placed upstream of the cutting device, such as those described in US Pat. No. 3,873,290.

The cutting device according to the invention can be arranged in various ways its arrangement will depend on the means used upstream to guide and stretch the son, as well as the implementation of the receiving device cut son. Thus, for example, Figure 1 shows a conventional arrangement for projecting vertically cut son.

The structure of the cutting wheel 19 according to two distinct embodiments are shown in FIGS. 2 and 3. The cutting wheel 19 comprises a hub 20 (visible in FIG. 1) and clamping flanges 21a, 21b enclosing the different fastening elements of the cutting blades 22.

The cutting blades 22, which have at each end a bevel, are inserted by these bevels in radial slots 23 crowns 24a and 24b. The rings 24a and 24b are concentrically mounted on the hub 22. The rings are concentrically mounted to the axis of rotation of the cutting wheel 19 by bearings and are clamped against each other between the clamping flanges 21a, 21b, the assembly being secured by locking members (screws for example). Flexible rings 25a, 25b made of elastomer are placed between the clamping flanges 21a, 21b and the sidewalls of the rings 24a, 24b, resting on the bevelled faces of the cutting blades.

When clamping the flanges 21a, 21b on the hub 22 by means of the screws, the elastomer rings 25a, 25b are compressed and thereby maintain the blades at the bottom of the radial slots 23 formed in the rings 24a, 24b.

The depth of the grooves 23 is greater than the height of the blades. The rings 24a and 24b are made of steel and they keep the blades apart. On the other hand, the clamping flanges 21a, 21b are made of steel and undergo a heat treatment (chromium supply) and serve as a support for the bottom of the blades. (In case of wear, it is easier and more economical, to recondition the flanges 21a, 21b rather than the crowns 24a, 24b)

On the other hand, there is disposed under and between the blades a deformable member 26, 27a, 27b, preferably of elastomer.

In the variant made in Figures 2 and 6, the cutting wheel 19 comprises a single deformable member 26 trapped between the clamping flanges 21a, 21b.

On the other hand, in FIGS. 3 and 7, it is a cutting wheel 19, called a wide wheel, particularly designed for production volumes of large chopped wire sections. This cutting wheel generally incorporates the components of the preceding cutting wheel and differs from them. by the addition of a second deformable member 27b (in fact the deformable member 26 has been separated into 2 parts 27a and 27b so as to be able to place a crown 29 of support), juxtaposed with the first 27a, the two deformable members 27a, 27b being axially separated by a spacer 28 allowing the blades 22 to have a point of support substantially equidistant point of their ends. A central ring 29 positioned coaxially with the spacer 28 is provided on its periphery with a plurality of radial slots 30 for the passage of the cutting blades 22.

The deformable member 26 (or the plurality of deformable members 27a, 27b in the case of Figure 3), located under the blades 22, consists of an elastomeric ring whose edges are erected over the entire diameter so to present a flat bearing surface so as to exactly match the cylindrical bearing surfaces of the rings.

The deformable members 26, 27a, 27b are integral with the ring forming the central part and protrude on its upper surface in the form of fins arranged at the pitch of the blades 22 and coming to be housed, with a certain clearance, in the free spaces between said blades. These bodies thus form a deformable fin crown, which is preferably monolithic; this ring, freely mounted without clamping, is positioned angularly and is kept centered not rigidly through the rings 24a, 24b.

It may be noted that during operation the upper face of the fins describes a cylindrical surface of revolution whose radius is different from that of the circle passing through the top of the cutting edge of the blades, and the difference between the two radii is a few tenths millimeters.

Of the assembly mode described above, it follows that the blades 22 are held at their ends, by means of flexible contacts, against the rigid contacts formed by the bottom of the radial slots 23 of the rings 24a, 24b and at least located between the ends, this point resting on the central crown door 29 (in the embodiment shown in Figure 2, the central point support does not exist). The cutting wheel 19 thus assembled is mounted on a rotating hub 20 shown in Figure 1, and is centered on it by means of a cone; the fixing of the cutting wheel on the shaft is ensured by screws.

The axis of rotation of the wing crown then coincides with his.

The deformable members 26, 27a, 27b annular and its fins are made of elastomer, for example polyurethane whose Shore hardness, scale A, is between 80 and 100. It is also conceivable a bi-material embodiment, the heart of the member in a first plastic with an overmolding of a second plastic material forming the fins, the first and second plastics material may have different mechanical properties, especially in terms of hardness.

As is apparent from FIG. 1, the cutting wheel 19 cooperates with an anvil wheel 18. The surface of the latter is covered with a flexible layer made of elastomer, for example made of polyurethane identical to that constituting the finned ring previously described.

The distance separating the axes of rotation of the drums 18 and 19 is adjusted (by applying a clamping pressure) so that the cutting edge of the blades penetrates shallowly into the coating of the bearing drum (the deformation of the elastomer layer limits the blade penetration).

It should be noted that the diameter of the finned crown is such that, when the cutting device is stopped, the upper faces of the fins do not exceed the level of the cutting edge of the blades. The motor movement is given preferably to the cutting wheel 19, which sets in motion the anvil wheel 18, mounted free on its axis. The movement is transmitted simultaneously by the action of the fins on the coating and by meshing resulting from the slight penetration of the blades in said coating.

It may also be noted that the thickness of the annular portion of the deformable member 26, 27a, 27b is determined according to the modulus dΥoung elastomer material constituting said member, so as to have a correct expansion of the fin (which serves point of support with the threads during the drawing phase, and then during the cutting phase into sections of cut threads), for the desired cutting speed ranges.

Figure 4 shows the operation of the device according to the invention adapted, the manufacture of relatively long cut strands.

According to this, the cutting wheel 19 comprises a finned ring whose upper faces reach at the cutting edge of the blades when the cutting wheel is stopped. When the cutting wheel reaches its normal rotation speed, the deformable member and the fins have undergone a slight radial expansion caused by the centrifugal force and, under this effect, the succession of the upper faces of the fins then forms a cylindrical surface of revolution. almost continuous, whose radius is greater than that of the concentric circle passing through the top of the cutting edge of the blades. In this case, the cylindrical surface of revolution and that of the coating come in contact, pinch the wire or son and cause their stretching, prior to cutting, by this single action. The pressure exerted by the fin on the glass wire is independent of the clamping pressure exerted between the axes of the two wheels (cutting and anvil). This pressure is constant and depends only on the nature and geometry of the deformable member.

The cutting wheel 19 also comprises blades whose spacing is such that the cutting work is performed by a single blade at a time.

In the actual cutting zone, the fins are pushed inwards under the action of the pressure exerted by the surface of the anvil wheel 18; under this action, the annular portion of the deformable member deforms radially inwardly in the space above the crown door.

This has the effect of gradually clearing the cutting edge of a blade which, penetrating into the peripheral coating of the anvil wheel, then cuts the wire and gives birth to the strand.

At the exit of the cutting zone, the latter is ejected by the fins which come out gradually under the action of the centrifugal force. In this variant, the rotation drive of the anvil wheel by the driving cutting wheel is provided essentially by the close cooperation of the cylindrical surface of revolution with that of the coating; this results in compression of the cut strand which is attenuated by the radial shrinkage of the wing crown and is not large enough to impair its integrity.

FIG. 5 shows the operation of another variant of the device according to the invention, suitable for cutting a wire into short lengths-for which the spacing of the blades is such that the cutting work is carried out simultaneously by at least two blades.

The integrity of the cut strands is all the more difficult to maintain as the contact points between the different elementary filaments forming the strand are fewer, which is particularly the case when reducing the length of the strands. The loss of cohesion can occur either as a result of the crushing of the strand between two surfaces strongly pressed against each other, or as a result of the shearing occurring during the cutting of a strand insufficiently maintained during this operation.

It is therefore necessary to avoid either a too strong clamping between the upper face of the fins and the surface of the coating of the wheel anvil, or on the contrary an absence of contact between these two surfaces, extreme cases in which a number of elementary filaments separate from the cut strands, resulting in the formation of fluff and rapid fouling of the device.

The operating mode of the cutting system illustrated in Figure 5 is as follows: the son are driven by the only traction resulting from its adhesion to the surface of the coating of the wheel anvil. In the actual cutting zone, the wires come into contact with the cutting edge of a first blade, then are trapped and held between the surface of the coating, the upper face of a fin and the next blade which initiates the cutting of the blade. strand. In contact with the coating, the fins are pushed back but slightly and under a lower pressure than in the previous case. The cut strand is thus maintained simply clamped between the two elastomeric surfaces and retains all its integrity.

At the exit of the cutting zone the fins emerge by ejecting the cut strands. In this variant the rotational drive of the anvil wheel by the driving cutting wheel 19 is ensured essentially by the penetration of the blades in the coating of the anvil wheel. For this reason it may also be advantageous to use a cutting wheel provided with blades arranged perpendicular to its periphery and inclined relative to its axis of rotation at an angle between 10 and 30 °

From the foregoing description it appears that the cutting device is set so that the cutting blades penetrate shallowly into the coating of the anvil wheel, this adjustment being corrected whenever the deterioration of the surface of said coating will require rework. The deformable member is chosen so that even after radial expansion caused by the centrifugal force, the upper faces of the fins describe a circle whose radius is slightly smaller than that of the concentric circle passing through the top of the cutting edge of the blades. In operation, a gap of 5/10 mm was measured.

Depending on this setting, the characteristics of the deformable member (s), and mainly the distance between the rays of the concentric circles described by the upper faces of the fins and the top of the cutting edge of the blades, will be chosen in particular. according to the desired length for the cut strands.

This difference is of the order of a few tenths of a millimeter, for example from -2 / 10 to + 3/10 millimeters taking as a reference radius that of the circle passing through the top of the cutting blades.

In addition to the length of the cut strands, it is obvious that other parameters, such as, for example, the moisture content of the yarn or the diameter of the filaments constituting said yarn, will also have to be taken into consideration in order to choose the finned crown the best. suitable for the intended manufacture. The device of the invention combines many advantages, including the following:

- The possibility of cutting several glass strands stretched from several dies at linear drawing speeds of several tens of meters per second.

The deformable fin member maintains the integrity of the wire sections and eject them out of the cutting area. The deformable fin member prevents clogging of the cutting wheel.

The cutting wheel which is driving and keeps a constant diameter, avoids the changes of adjustment of the speed of rotation.

The cutting wheel is easy to assemble and disassemble when it becomes necessary to change one or more blades. The majority of the parts constituting it is symmetrical, which facilitates the assembly and decreases the number of pieces in stock. The structure of the cutting wheel also has the advantage of being able to modify the length of the sections of wire by a quantity that is a multiple of the pitch of the grooves. (It is possible to alternate between the cutting blades, non-cutting blades, in order to vary the cutting pitch) Indeed, for a given deformable fin member, the adjustment of the length can be easily obtained by inserting between two successive cutting blades one or more blades devoid of cutting edge and whose height is such that they do not touch the surface of the support drum in the cutting zone. The insertion of these blades is intended to keep in place the deformable fin member and avoid significant deformations that would cause its rupture.

At the limit, it is possible to equip the blade drum with a single cutting blade and thus obtain sections whose length is equal to the circumference of said drum.

In a more common way, one obtains without difficulty, from son stretched at speeds between 30 and 50 meters per second, sections whose length can vary between 3 millimeters and about 50 millimeters.

Claims

1- cutting wheel (19) for cutting continuous son (1 1) in sections (14) of a predetermined length, comprising a support member consisting of a rotary drum equipped with blades (22) arranged perpendicularly to its periphery and, between the blades (22), organs to ensure under the effect of the centrifugal force compression of the son (1 1) against the surface of a support drum (18), and then cutting the son in sections (14), and the ejection of the cut sections, the members providing the compression of the son being constituted by fins secured to a deformable ring (26, 27a, 27b) disposed under the base of the blades (22) and the axis coincides with the axis of rotation of said cutting wheel (19) is characterized in that the deformable ring (26, 27a, 27b) comprises on each side a parallel right flank extending from the base of the deformable ring (26, 27a, 27b) to the base of the fins.

2- cutting wheel (19) according to claim 1, characterized in that the deformable member (26, 27a, 27b) is at least in two parts, a spacer (29) separating the two parts and being mounted concentrically relative the axis of rotation of the drum and the spacer (29) serving as a fulcrum to said blades (22) between their two ends.

3- cutting wheel (19) according to one of claims 1 or 2, characterized in that the blades (22) are on the one hand, immobilized at their ends and secondly rest at the level of at least one point between its extremities.

4- cutting wheel (19) according to one of the preceding claims, characterized in that the ends of the blades (22) fit into slots (23) formed in two rings (24a, 24b) mounted face to face, concentrically to the axis of rotation of the drum. 5- cutting wheel (19) according to one of the preceding claims, characterized in that the ends of the blades (22) are held at the bottom of the slots (23) formed in the rings (24a, 24b) using a pair of elastomer rings (25a; 25b) and a pair of flanges (21a, 21b), said flanges (21a, 21b) being adapted to induce clamping stresses at the elastomeric rings (25a, 25b).

6. cutting wheel (19) according to one of the preceding claims, characterized in that the flanges (21a, 21b) and the rings (25a, 25b) of elastomer are mounted face to face, concentrically to the axis of rotation drum.

7- Cutting wheel (19) according to one of the preceding claims, characterized in that all or part of the parts selected from the flanges (21a, 21b), the rings (25a, 25b) made of elastomer, the rings (24a, 24b), are symmetrical parts.

8- cutting wheel (19) according to one of the preceding claims, characterized in that the deformable member (26, 27a, 27b) comprises a ring provided at its periphery with a plurality of fins, the fins and the ring forming a monolithic whole.

9- cutting wheel (19) according to one of the preceding claims, characterized in that the fins and the ring are made of different materials.

10- Cutting wheel (19) according to one of the preceding claims, characterized in that a space is provided between 2 contiguous fins and is delimited by the connecting surface between the base of the fins and the base of a blade ( 22). 1-cutting wheel (19) according to one of the preceding claims, characterized in that during operation the upper face of the fins describes a cylindrical surface of revolution whose radius is different from that of the circle passing through the top cutting edge (22).

12- Cutting wheel (19) according to the preceding claim, characterized in that the distance between the two radii is a few tenths of millimeters.

13- Cutting machine for the manufacture of cut yarns for technical use, in particular yarns of thermoplastic material and in particular glass yarns, said machine comprising a three-dimensional chassis having three or more sides, at least one integral cutter assembly of one of the sides of said frame, said cutter assembly using a cutting wheel according to any one of claims 1 to 12.